I seem to recall that the US army used the M4A2 model for their DD tanks for the Normandy Invasion.
I do not believe you recall correctly. But I am willing to be convinced, if you have some further information to share.
My understanding is that all US Army DD conversions were done on M4A1s.
The initial suggestion was to use the latest / newest technology of Sherman available for DDs. In January 1944 a request was made for the first 160 production units of the M4A1(76mm) production, for DD conversion for D-Day.
However this request was rejected, as all of the initial production M4A1(76) were already spoken for. (Oddly enough the first 100, shipped to the UK, were left behind on D-Day because the units they were offered to didn't want them.)
Consequently 350 available M4A1(75mm) were used. Pardon me for being explicit here, but in case some of our forum members do not know, the M4A1 was the only Sherman variant with a cast hull. The edges of the hull appear rounded. All other variants had welded hulls, with clear sharp edges.
It appears most or all of the M4A1s used for the DD conversions were Pressed Steel Car late-1943 production vehicles. These vehicles had the rather distinctive combination of additional characteristics of a raised turret bustle, cast-in hull side re-enforcing plates (vs. welded-on applique plates), and enlarged driver and co-driver hatches.
Here is a pic of the procurement order for the 350 tanks to be converted as DDs. It clearly identifies them as M4A1s.
This picture is of a D-day DD Sherman raised from the seabed off of Normandie, and now on display at Torcross, England. It is clearly an M4A1.
This picture is of a D-Day DD Sherman raised from the seabed, and now on display at Port-en-Bessin, France. It is clearly an M4A1.
(Pictures from this excellent site with details of the various Sherman sub-models and even the "minutia": link )
Three US Army independent tank battalions operated DD Shermans on D-Day: the 70th, 741st, and 743rd. I have found several pictures of US Army DD Shermans in action in the days and weeks following D-Day. All that I have found so far are M4A1s. But these pics do not identify the specific units that operated the tanks. I have later-war pictures of 75mm Shermans which clearly identify them as being operated by the 70th Tank Battalion. They all show M4A1s. But I have not found any pics of 75mm Shermans identified as being operated by the 741st and 743rd, despite my searching.
So after all of that, with both the evidence and the gaps in my research, I'm reasonably confident that US Army DDs were all M4A1s.
But please believe that I have exactly NO sarcastic, satirical, or otherwise hostile intent, explicit or implied, when I say that if you have information about M4A2s in US Army service in ETO, I'd love to see it.
I have no interest in proving a pre-conceived position. My interest is in learning and understanding what actually happened. It seems that so many people these days can't even believe that not all writing or discourse is partisan argumentation. But there's nothing wrong, in my world view, with learning something new every day. And doing it happily.
-Mark
(aka: Mk 1)